Speciation and diversification of parasite lineages: an analysis of congeneric parasite species in vertebrates |
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Authors: | Robert Poulin |
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Institution: | (1) Department of Zoology, University of Otago, Dunedin, New Zealand (fax |
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Abstract: | The evolutionary diversification of living organisms is a central research theme in evolutionary ecology, and yet it remains
difficult to infer the action of evolutionary processes from patterns in the distribution of rates of diversification among
related taxa. Using data from helminth parasite communities in 76 species of birds and 114 species of mammals, the influence
of four factors that may either be associated with or modulate rates of parasite speciation were examined in a comparative
analysis. Two measures of the relative number of congeneric parasite species per host species were used as indices of parasite
diversification, and related to host body mass, host density, latitude, and whether the host is aquatic or terrestrial. The
occurrence of congeneric parasites was not distributed randomly with respect to these factors. Aquatic bird species tended
to harbour more congeneric parasites than terrestrial birds. Large-bodied mammal species, or those living at low latitudes,
harboured more congeneric parasites than small-bodied mammals, or than those from higher latitudes. Host density had no apparent
association with either measures of parasite diversification. These patterns, however, reflect only the present-day distribution
of parasite diversification among host taxa, and not the evolutionary processes responsible for diversification, because the
apparent effects of the factors investigated disappeared once corrections were made for host phylogeny. This indicates that
features other than host body size, host density, latitude, and whether the habitat is terrestrial or aquatic, have been the
key driving forces in the diversification of parasitic helminth lineages.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | adaptive radiation comparative analysis gastrointestinal helminths host body mass latitude phylogeny species flocks |
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